By Isabel Ivanescu with Andrew Greco
Key Takeaway: Turkey may have agreed to cede control of territory in southern Idlib to pro-Assad forces in a meeting with Russia on September 16. If the reports of a deal are true, a pro-Assad offensive is likely imminent. Turkish-backed opposition forces and al Qaeda linked elements may fight back against advancing Russian-backed regime forces even without Turkish support. Turkey is most likely to cede the territory south of the M4 highway, a zone in which Turkey had already agreed to allow Russian patrols in March but retained forces, including artillery units, that precluded a full regime takeover. ISW warned on March 18 that this situation was likely untenable because al Qaeda-linked forces rejected Russian presence. Turkey could face backlash from al Qaeda-linked elements, local civilians, and even Turkish-backed opposition forces for negotiating away opposition-held territory.
Tripwire: Russian state-owned news outlet RIA Novosti reported that Turkey agreed to reduce troop numbers in, and withdraw some heavy artillery from, greater Idlib Province as Turkish and Russian military delegations met in Ankara on September 16 to discuss Syria. Other sources, including Turkish media and the usually-credible Asharq al-Awsat, subsequently corroborated these reports. A negotiated removal of Turkish forces from areas of Idlib, if it does occur, would reflect a revision to the de-escalation agreement signed by Russia and Turkey on March 5 and would indicate a renewed pro-regime offensive is imminent.
Pattern: A series of recent events indicate Russia and Turkey have been negotiating an agreement providing for a partial Turkish withdrawal from greater Idlib.
- Turkey withdrew hundreds of Turkish Armed Forces (TSK) special forces and infantry and Turkish-backed opposition fighters from southern Idlib towns in the Jabal Zawiya area (Abdita, Ahsam, Al-Magara, and Beliun) on September 8. Turkey claimed the withdrawal was a redeployment related to Turkey’s ongoing maritime disputes with Greece, but Turkey may have used its dispute with Greece as cover for actions consistent with an impending deal with Russia in Idlib. Turkey has previously redeployed Syrian fighters from Idlib to Libya. Turkey’s redeployment of TSK forces from greater Idlib to another theater marks an inflection, however.
- Turkey reduced the frequency of its military logistics convoys. Turkey typically sends convoys carrying supplies and rotating troops into its military positions in greater Idlib every 1-2 days, but reduced this activity to only three convoys in the past 13 days (two on September 10, one of September 18). Turkey’s force reduction and decreased activity along ground lines of communication may have been a Turkish demonstration of good faith as negotiations with Russia were ongoing or an early move to implement a soon-to-be-finalized agreement to reduce Turkey’s presence in the area.
- The Assad regime organized violent protests outside Turkish observation points in Morek, northern Hama Province; Sarman, southeastern Idlib Province; and potentially elsewhere on September 16. The regime attempted to keep its role in these protests secret by encouraging protesters to dress in civilian clothing. These protests likely represent a regime effort to exert pressure on Turkish military positions and emphasize the unpopularity of the Turkish presence in regime-held areas of greater Idlib. The regime likely sought levy an implied threat against Turkish forces, as Russia pursued a deal for the handover of more terrain.
Two recent Russian statements signal that a resumption of the pro-regime offensive in greater Idlib may be imminent.
- Russian foreign minister Sergei Lavrov expressed confidence that Turkey and Russia would succeed in “liberating” Idlib Province from terrorists in a press conference on September 7. The statement was oddly optimistic following a string of Salafi-jihadist attacks on Russian-Turkish joint patrols along the M4 highway from late July to early September.
- Russian General Alexander Greenkiewicz, who heads the Russian Center for Reconciliation in Syria, claimed on September 11 that al Qaeda-linked Hayat Tahrir al-Sham is planning a chemical attack on Jabal Zawiya. Russia has frequently accused anti-Assad forces of planning chemical attacks without evidence and has deliberately confused the information environment in the past to obscure the Assad regime’s exclusive conduct of such attacks. Russia could be preparing the information environment to justify a pro-regime offensive. In a low-probability but dangerous scenario, Russia may have issued the statement to muddy attribution knowing the Assad regime is itself planning a chemical attack on Jabal Zawiya.
Turkey’s foreign minister, Mevlüt Çavuşoğlu, denied on September 16 that negotiations with Russia had been productive and emphasized the need for a political solution in Idlib. Çavuşoğlu may be trying to temporarily conceal the details of an agreement with Russia in order to preserve Turkey’s reputation among greater Idlib’s population and avoid backlash from opposition groups.
Pro-Assad forces have brought enough reinforcements to the Idlib frontlines since the March 5 de-escalation agreement between Russia and Turkey to enable an attack. Low-level frontline fighting and limited Russian and regime artillery and airstrikes have all persisted despite the de-escalation agreement. The operational tempo of pro-regime attacks increased in July as pro-Assad forces intensified their shelling of frontline towns and probing attacks against opposition defenses. Russian airstrikes and regime shelling of opposition positions now an almost daily occurrence. This increase in operational tempo likely represents condition setting by Russia and the Assad regime. ISW assesses that resumption of a Russian-backed regime offensive against greater Idlib is only likely if Russia receives Turkey’s permission in exchange for concessions elsewhere. ISW therefore does not assess a renewed pro-regime offensive to be imminent on the basis of this increased but limited battlefield activity alone.
Assessment: Pro-regime forces will resume their campaign to retake greater Idlib in coming weeks if Turkish forces do indeed withdraw from portions of Idlib Province as part of a negotiated agreement.
The most likely location for a forthcoming pro-Assad offensive is the Sahl al-Ghab and Jabal Zawiya areas south of the M4 highway, where pro-regime forces have focused their airstrikes, shelling, and frontline attacks. If Turkey did reach a deal with Russia, it likely agreed to pull its forces back to the M4 highway security corridor, effectively ceding everything south of the M4 security corridor to the Assad regime. Turkey’s September 8 withdrawal already removed some of Turkey’s forces from this area.  The zone south of the M4 is Turkey’s least defensible territory in northwest Syria – regime forces are heavily concentrated along this frontline, the terrain is comparatively flat, and the frontlines have evolved such that the area is vulnerable to encirclement. Reports that Turkey intends to keep its observation posts in Sahl al-Ghab and Jabal Zawiya are unsurprising and do not preclude the possibility of a deal to cede control. Turkey has previously maintained observation posts even when pro-Assad forces have recaptured the surrounding territory and isolated them. Turkish retention of observation posts south of the M4 security corridor as pro-Assad forces prepare to take the area would fit the pattern.
The Assad regime is likely to attempt to collapse the opposition pocket south of the M4 highway in a double envelopment with a western prong tracking north from Jabal Shahshabo and an eastern prong tracking north from Ma’arat al-Numaan before linking up near Ariha. Seizing the territory in question will not be an easy fight for the Assad regime; however, with Russian backing, regime forces will likely overpower the forces of HTS and smaller opposition groups absent Turkish support.
It is unclear what concessions Turkey may have gained from Russia in exchange for the withdrawal. Russia might have promised to coerce the Assad regime into permitting a Turkish offensive into the jointly regime and Syrian Democratic Forces dominated Tel Rifaat area. A Syrian state-linked outlet claimed on September 17 that Russia refused the Turkish delegation’s request to hand over the major population centers of Tel Rifaat and Manbij during the September 16 meeting. This source has an incentive to lie to avoid the appearance of regime weakness. Turkey shelled areas near Tel Rifaat on September 17. Russia may also have made concessions pertaining to northeast Syria, Libya, defense cooperation, or other areas in which both parties have interests.
Implications: It is not assured that the Assad regime could readily advance beyond the M4 highway, particularly if Turkey is determined to defend it. However, the regime could gain significant territory by seizing Jabal Zawiya and Sahl al-Ghab and establishing a new defensible line, which would likely render its previous gains irreversible. Turkey’s willingness to make deals may create openings for further regime gains in the subsequent months or years. Further, a regime seizure of this area could enable it to use the M4 highway to link this new control zone in Ariha to regime-held Saraqib. The regime may also be able to create a vulnerable opposition salient to the west of Jabal Shahshabo, positioning itself to take difficult terrain more easily.
A Turkish withdrawal from southern Idlib would likely trigger blowback from jihadists and the local population. HTS has increasingly aligned itself with Turkey in order to retain Turkey’s support in defending Idlib and has attempted to curtail the activities of hardline Salafi-jihadist groups who seek to expel Turkish forces. A major Turkish territorial concession could cause HTS to reverse this position. Hardline groups will likely scale up attacks on Turkish forces in either case. The population’s response to the Turkish presence in greater Idlib has been mixed. The goodwill of local supporters of the Turkish presence is premised on Turkish defense of greater Idlib against the Assad regime.
Indicators: ISW will be watching for a physical withdrawal of Turkish forces and artillery from Idlib in accordance with Russia’s claimed deal as well as for any effort to create a new, defensible Turkish frontline. Intense Russian airstrikes intended to soften opposition defenses would indicate that a ground push by pro-Assad forces could follow in the coming days or weeks. The presence of key regime commanders from elite military units such as the Russian-backed Syrian Arab Army (SAA) 25th Special Tasks Division (aka. Tiger Forces) and the SAA 4th Division along the frontlines would also indicate an imminent regime offensive. The lack of an actual withdrawal of Turkish forces from southern Idlib or outright Turkish and Russian repudiation of the reports of an agreement would indicate that negotiations failed.
 https://english.aawsat.com/home/article/2513046/russia-seeks-reduce-turk… ; https://npasyria.com/en/?p=46907; https://hawarnews.com/en/haber/russia-seeks-to-reduce-turkeys-presence-i… ; https://www.syria.tv/%D9%85%D8%B1%D9%83%D8%B2-%D8%AD%D9%85%D9%8A%D9%85%D…
 https://www.syriahr.com/en/183382/ ; https://www.syriahr.com/en/182775/ ; https://www.syriahr.com/en/182338/ ; https://www.syriahr.com/en/181996/ ; https://www.syriahr.com/en/184542/ ; https://www.radioalkul.com/p341264/ ; https://www.baladi-news.com/ar/articles/65204/%D8%A8%D8%B9%D8%AF-%D8%A7%…
 https://twitter.com/tcsavunma/status/1306196200014647296 ; https://twitter.com/smmsyria/status/1306174046908932096 ; https://www.syriahr.com/en/184283/ ; DNGTS: https://www.syria.tv/%D9%86%D8%B8%D8%A7%D9%85-%D8%A7%D9%84%D8%A3%D8%B3%D… ; DNGTS: https://www.almasdarnews.com/article/turkey-claims-troops-were-attacked-… ; DNGTS: https://www.enabbaladi.net/archives/416791
 https://www.radioalkul.com/p339969/ ; http://www.understandingwar.org/backgrounder/syria-situation-report-augu…
 DNGTS: https://www.radioalkul.com/p339969/ ; DNGTS: https://www.syria.tv/%D9%85%D8%B1%D9%83%D8%B2-%D8%AD%D9%85%D9%8A%D9%85%D…
 DNGTS: https://shaamtimes.net/253815/%d9%85%d9%88%d8%b3%d9%83%d9%88-%d8%aa%d8%b… ; https://www.almasdarnews.com/article/russian-jets-launch-biggest-attack-… ; https://www.radioalkul.com/p339475/
 https://www.syriahr.com/en/184413/ ; DNGTS: https://www.enabbaladi.net/archives/397739 ; https://www.qasioun-news.com/ar/articles/228903/%D8%A7%D8%B4%D8%AA%D8%A8… ; https://www.alaraby.co.uk/%D8%A5%D8%AF%D9%84%D8%A8-%D8%AA%D8%B5%D8%B9%D9… ; https://www.radioalkul.com/p332640/